1. Field of the Invention
This invention is directed to improving the operation of barricade or arrester net gears of the type designed for retaining an aircraft at the end of runways notably in case of failure of the aircraft braking system.
2. Description of the Prior Art
Net gears or structures comprising superposed elementary nets have already been proposed in the art, each elementary net consisting of spaced vertical straps tensioned between horizontal straps. When the aircraft engages this net gear, the vertical straps are bent on the aircraft wings somewhat like the belts of a harness, so that each elementary net remains fastened or clings to the aircraft and cannot slip off. This result is obtained so long as the relative spacing of the vertical straps is not excessive and remains within reasonable limits, so that at least one vertical strap remains on each wing. In the case of short-span aircrafts or aircrafts having a pronounced delta configuration, a very reduced relative spacing of these vertical straps is required, so that their number must be increased accordingly, with the attendant shortcomings listed hereinafter:
Firstly, the necessary increment in the number of straps increases the weight and cost of the net gear, and also its wind resistance.
Furthermore, a greater number of straps may cling to inadequate locations or parts of the aircraft, such as aerials, wing slots or jet-engine slots, jet-engine inlets, etc.
Finally, a greater number of vertical straps may be struck by forwardly producing portions or elements of the aircraft, with the likelihood of causing a greater number of horizontal straps to move up or down in front of undesirable parts such as the front or nose landing wheel or undercarriage, or the pilot's cockpit. Now this last objection is of particular importance for cases are known wherein an excessive number of lower horizontal straps engaged by the front undercarriage caused serious damages thereto or even the breakage thereof.